1. Field of the Invention
The present invention relates to a lead terminal structure of a resolver, particularly a high-quality resolver with improved assembling efficiency so as to enhance a mass productivity.
2. Description of the Related Art
In a conventional resolver, a lead wire is fixed in a slot of a stator core and the end portion of a coil is connected to the lead wire by soldering. In the resolver thus constructed, connecting the lead wire with the coil by soldering has been troublesome, the condition in connecting by the soldering is varied, thereby making the workability and reliability difficult to improve.
For solving the above problems, Japanese Unexamined Patent Publication No. 11-98747 can be shown as one example. Such a lead terminal structure of a resolver is shown in FIG. 7.
In FIG. 7, the entire shape of a stator core 51 is ring-shaped and constructed in a multilayer form, and, for example, a conventional coil 52 of a single-phase excitation and two-phase output type is provided in a slit (not shown) along the inside edge of the stator core 51. An under-cover 53 U-shaped in section is provided at an end portion 51A of the stator core 51. On the upper surface of the undercover 53, at least one terminal pin is held and a pin-holder 55 made of a plastic material is provided.
Protrusions 54a of terminal pins 54 pass through the pin-holder 55 and are protruded upward, and the end portion of the coil 52 is connected to the protrusions 54a. Furthermore, the terminal pins 54 are connected to a connector 56 via a lead wire 57 by a conventional solderless contact. Moreover, although not illustrated, the under-cover 53 is inserted in a slot of the stator core 51.
A rotor 58, which is constructed in a ring-shaped and a multilayer form, and is a variable reluctance type (VR type) in this embodiment, is rotatably provided inside the stator core 51, and ring-shaped first and second coil protection covers 510 and 511 are provided on both surfaces of the stator core 51. This first coil protection cover 510 covers the upper surface of each coil 52 and also concurrently covers the pin-holder 55 and the protrusions 54a. A bulging portion 510a protruded to cover the protrusions 54 is integrally formed at a place where the protrusions 54a are provided. An end portion 510b of the first coil protection cover 510 is fixed to the pin holder 55 by welding, an adhesive, etc. The second coil protection cover 511 covers the under surface of each coil 52 and its end portion 511a is fixed to the under-cover 53 by welding, an adhesive, etc.
In the lead terminal structure of a resolver, the pin-holder 55 holding terminal pins 54 to which the lead wire 57 is connected is provided on the under-cover 53 arranged in the stator core 51, and the coil 52 is directly connected to the terminal pins 54. The first coil protection cover 510 covers the upper surface of each coil 52 and concurrently covers the pin-holder 55 and the protrusions 54a and is fixed to the pin-holder 55 by welding, an adhesive, etc. Therefore, those members described above can be effectively protected from mechanical damages but not enough for poor surroundings such as moisture, vibration, impact, etc.
The conventional lead terminal structure of a resolver enabling to withstand the poor surroundings is shown in FIG. 8. In the structure, problems due to moisture, vibration, impact, etc., are solved such that the end portion of the stator coil and the lead wire are fixed by using a potting material.
In FIG. 8, the stator core 51 is provided with a lead-wire-fixed portion 64. A wiring board (not shown), to which the end portion of the stator coil (not shown) and lead wires 57 are connected, is provided inside the lead-wire-fixed portion 64. The potting material is poured into the lead-wire-fixed portion 64 so that the lead wire 57 may not be twisted and each of them may stand upright and with a substantially equal distance therebetween by using lead-wire fixing jigs 60 and 61 for fixing the lead wires. That is, the lead-wire fixing jig 60 is fixed to the lower end portion of the lead-wire-fixed portion 64 by screws (not shown), etc., so that the lead-wire-fixed portion 64 may be horizontal. The lead wires 57 are made to pass through notches 65 provided at the location where the lead-wire fixing jigs 60 and 61 contact each other. The lead-wire fixing jig 61 is fixed to the lead-wire fixing jig 60 by using screws 62a and 62b. Thus, the lead wires 57 are fixed to the fixing jigs 60 and 62. Then, the end portion of the stator coil and the lead wires 57 are fixed with a potting material 63 such that a potting material is poured into the lead-wire-fixed portion 64. After the potting material 63 has been cured, the lead-wire fixing jigs 60 and 61 are removed from the lead-wire-fixed portion 64.
The lead terminal structure of the resolver shown in FIG. 8 solves problems due to moisture, vibration, impact, etc. except the following. That is, one set of lead-wire fixing jigs 60 and 61 will be required per resolver until the potting material 63 has been cured. Furthermore, an additional work for fixing the lead-wire fixing jigs 60 and 61 to a resolver, for example, the lead-wire-fixed portion 64 is required, and after the potting material 63 has been cured, the lead-wire fixing jigs 60 and 61 should be removed from the lead-wire-fixed portion 64. Moreover, since the lead wires are fine, the work efficiency making the lead wires 57 passed through the notches 65 becomes lessen while it also takes time to properly arrange the lead wires 57 with an equal space therebetween. In case each of the lead wires is not equally spaced such as touching with each other, that may cause faulty insulation.
Furthermore, as shown in FIG. 9, a portion P where the lead wire 57 protrudes from the surface of the potting material 63 and is in touch with the potting material 63 has sharp edges when the potting material is cured. Therefore, after the potting material has been cured, when the lead wire 57 is bent, the lead wire 57 is easily damaged such as a break, a short circuit, etc.